Methods of making paper tissue, towel, and the like are well known, including various features such as Yankee drying, throughdrying, fabric creping, dry creping, wet creping and so forth. Conventional wet pressing processes (CWP) have certain advantages over conventional through-air drying processes (TAD) including: (1) lower energy costs associated with the mechanical removal of water rather than transpiration drying with hot air; and (2) higher production speeds which are more readily achieved with processes which utilize wet pressing to form a web. On the other hand, through-air drying processes have become the method of choice for new capital investment, particularly for the production of soft, bulky, premium quality tissue and towel products.
Fabric creping has been employed in connection with papermaking processes which include mechanical or compactive dewatering of the paper web as a means to influence product properties. See U.S. Pat. Nos. 4,689,119 and 4,551,199 of Weldon; U.S. Pat. Nos. 4,849,054 and 4,834,838 of Klowak; and U.S. Pat. No. 6,287,426 of Edwards et al. Operation of fabric creping processes has been hampered by the difficulty of effectively transferring a web of high or intermediate consistency to a dryer. Note also U.S. Pat. No. 6,350,349 to Hermans et al. which discloses wet transfer of a web from a rotating transfer surface to a fabric. Further patents relating to fabric creping with a fixed gap transfer or rush transferring as the operation is known in the art include the following U.S. Pat. Nos. 4,834,838; 4,482,429; 4,445,638, as well as U.S. Pat. No. 4,440,597 to Wells et al.
In connection with papermaking processes, fabric molding has also been employed as a means to provide texture and bulk. In this respect, there is seen in U.S. Pat. No. 6,610,173 to Lindsay et al. a method for imprinting a paper web during a wet pressing event which results in asymmetrical protrusions corresponding to the deflection conduits of a deflection member. The '173 patent reports that a differential velocity transfer during a pressing event serves to improve the molding and imprinting of a web with a deflection member. The tissue webs produced are reported as having particular sets of physical and geometrical properties, such as a pattern densified network and a repeating pattern of protrusions having asymmetrical structures. With respect to wet-molding of a web using textured fabrics, see, also, the following U.S. Pat. Nos. 6,017,417 and 5,672,248 both to Wendt et al.; U.S. Pat. Nos. 5,505,818 and 5,510,002 to Hermans et al. and U.S. Pat. No. 4,637,859 to Trokhan. With respect to the use of fabrics used to impart texture to a mostly dry sheet, see U.S. Pat. No. 6,585,855 to Drew et al., as well as United States Publication No. US 2003/0000664.
Structures with local variations in basis weight are also known in the paper making art. These structures are reported to conserve fiber and provide areas of elevated absorbency. There is disclosed, for example in U.S. Pat. No. 6,136,146 to Phan et al. entitled “Non-through Air Dried Paper Web Having Different Basis Weights and Densities” a paper web including at least two regions of different densities and two regions of different basis weight. The paper web includes a relatively high basis weight continuous network region and a plurality of discreet, relatively low basis weight regions dispersed throughout the relatively high basis weight continuous network regions and a plurality of discreet, intermediate basis weight regions circumscribed by the relatively low basis weight regions.
U.S. Pat. No. 5,503,715 to Trokhan et al. entitled “Method and Apparatus for making Cellulosic Fibrous Structures By Selectively Obturated Drainage and Cellulosic Fibrous Structures Produced Thereby” also discloses a cellulosic web having different basis weight regions. This structure is a paper having an essentially continuous high basis weight network and discreet regions of low basis weight formed by using a forming belt having zones with different flow resistances. The basis weight of a region of the paper is generally inversely proportional to the flow resistance at the zone of the forming belt upon which the web is formed.
U.S. Pat. No. 4,942,077 to Wendt et al. entitled “Tissue Webs Having Irregular Pattern of Densified Areas” discloses creped tissue webs having at least a machine direction broken line pattern of individual densified areas containing higher mass concentrations of fiber.
Two and three-ply absorbent products are described in the following: U.S. Pat. No. 6,746,558 to Hoeft et al. entitled “Absorbent Paper Product of at Least Three Plies and Method of Manufacture”, U.S. Pat. No. 5,215,617 to Grupe entitled “Method for Making Plied Towels”, and U.S. Pat. No. 4,803,032 to Shultz entitled “Method of Spot Embossing a Fibrous Sheet.”
It is known that the embossing/ply-attachment process in towel production provides voids between the two attached plies which hold water that is absorbed through the sheet. With respect to sheets made by CWP processes, these voids are produced by attaching two sheets that were dried in the flat state and then dry-creped. Wetting these types of towels causes them to expand and then collapse back to their as-dried states. Therefore, truly high performance towels are made using the TAD process where the sheet is dried in the (fabric) molded state. When wetted, TAD towels can actually expand, increasing their water holding capacity and the visual perception of higher performance-like that of a dry sponge.
There is provided in accordance with the present invention absorbent products which exhibit sponge-like response to sorbed liquid without the need for throughdrying.